TNT-Audio Readers' Corner
Monthly section devoted to your letters, positive and negative feedback about everything related to Audio and HiFi.

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Lenco L75 tonearm repair?
Hi Roger,
And thanks for a nice article on tweaking the L75 and tonearm. As the proud owner of a drooping one, I wondered if anyone has tried sawing the offending bit off and sticking something inside to attach it to the rest? Not a wire but just a glued metal rod or something like that if it is even possible.
Giving mine a refurb and a new plinth and would like to fix the arm, but making a bit prettier than the outside rod or glue/tape.
Regards,
Mikael - E-mail: MikaelSeierup (at) outlook.com

RMcC
Hi Mikael,
No doubt some people have tried to do as you suggest however I have never heard of anyone who has done that with success. I think that if one had access to a precision machine shop it would be possible to invent something to securely attach together the 2 pieces but, in my opinion it is not worth the effort. It would probably be easier just to make a new armwand!
If you invent a new solution TNT-Audio certainly would like to hear about it.
Roger McCuaig

Some Lenco tonearm advice needed
Hi Roger,
Thanks for your brilliant article on repairing the Lenco tonearm. I have a Goldring Lenco GL69 with its original tonearm with the square counterweight. The back is definitely drooping, would the same repair you did work on this tonearm? And I guess I'll need to find a way to get to the v blocks? They look quite old. I had thought about putting a linn basik straight tonearm in but that might mean losing the lift mechanism on the Lenco that's really great.
Any advice would be greatly appreciated.
Greetings from London UK.
Best wishes
Chris - E-mail: chrisredgrave (at) hotmail.com

[Lenco_tonearm]

RMcC
Hi Chris,
I am very happy that you enjoyed my article. The internet is saturated with DIY Lenco stuff so I wasn't sure that another one would be appreciated! I have no experience with the GL69 however I looked at a few photos this morning and it appears to me that the armwand is the same and therefore you should be able to apply the same remedies that I outlined for the L75 arm. If you remove the counterweight and bend the counterweight shaft down a bit and you see a very thin steel wire holding the 2 rods together, then you can certainly conclude that it's the same as the L75. Beware, if you bend it too much, say 40 degrees, you could snap the wire! Have you been able to determine if your unit takes the same V-blocks as the L75/78? If not you might want to check that. No doubt it has been posted on the LencoHeaven web site.
I recently installed a rebuilt Linn Akito arm on my "Big Lenco" and it is performing exceptionally well. You should see a DIY article on this subject appear sometime soon on TNT-Audio.com. Here's something that you can do with your Linn Basik if you are interested in experimenting a bit. Leave the original Lenco cueing lever in place but remove the Lenco cueing arm. Just unscrew the height adjustment screw all the way out and the cueing arm will lift out from the top. You can then try the Basik without interference from the original cueing parts and easily go back to the Lenco arm by just screwing back in the removed Lenco part. Of course I have not addressed here the question of installing the Basik arm. One solution that I have used in the past for Jelco arms is the get an aluminum mounting sleeve (similar to the Lenco part) made in a local machine shop. It works perfectly.
Hope this helps.
Roger McCuaig

SS 3602 on Maverick D1
Hi!
After reading your review about Sparkos Labs SS 3602 Dual Op Amp, I tried them on my Maverick D1. At first it was great, but soon something went wrong. Is it possible that the regulator of the maverick is too weak to handle them (there is only 2 on the D1).
Cheers!
Marcel - E-mail: marcelroyer.59 (at) hotmail.com

LC
Dear Marcel,
sorry to hear something went wrong with this upgrade. Mike wrote in that review:

“The Maverick uses the cheap and functional 78XX and 79XX voltage regulators to supply the op amps. There are numerous options for better quality regulators so I asked Andrew from Sparkos if there was any benefit to upgrading the regulators. The response was interesting, as the Sparko's op amps are operating in class A, their demand on the supply is much more constant. With the regular op amps operating in class A/B mode, as the output voltage of the op amp increases so does the current demand and the supply must follow this. This means the regulators must have the ability to hold the voltage constant whilst at the same time deliver varying current at audio frequencies. Most regulators were not designed to meet these varying demands. I may explore voltage regulator upgrades for the Maverick in a future article.”
Perhaps that's the reason for the failure, the regulators on your D1 weren't up to the task. I'd contact Sparkos Labs to see if they can give any further hint or suggestion.
Keep us updated!
Lucio Cadeddu

Doge 7 DAC
Hi Roger,
I just re-read the review and I see now you meant that the unit sounded more transparent when you ran it directly into your power amp, thus bypassing a separate preamp. So, as I suspected, the tube output stage in the Doge is in play even when using the unit in the volume control mode. Sorry for the initial misinterpretation.
Thanks,
Brad - E-mail: bradwkap (at) yahoo.com

RMcC
Hi again Brad,
Yes, you have got it right, I can run without a preamp and just use the tube analog output of the DAC. Regarding the digital volume control question that you mentionned in your previous email, I can give you a bit more detail on that topic. I understand that ESS has published some data on this however I was not able to find it this morning. The information that I am providing here comes from a third party source. I cannot say that this is 100% acurate however it appears to be reliable.
The digital volume control is done inside the DAC chip. When the Doge 7 is set to preamp mode, the ESS DAC chip applies a multiplier to all the digital data. This is done before the oversampling filter and results in a new digital value. The last bit produced this way must be rounded to 16 or 24 bits (and dither applied) and the remainder is lost. So the least significant bit of the data has a quantization error. For a 16 bit signal we are looking at a difference at -96 dB (barely audible) and for a 24 bit word we are at -144 dB which is way below the noise floor of any gear!
Hope this helps.
Roger McCuaig

Lenco L75 Corian Platters
Hi Roger, Thanks for the review on this Lencohell upgrade. I'm also in Canada in the GTA area myself. I'm also in the process of building my 4 Lencos. Have you used the CLD plinth design as I've previously done and has since been sold. I would love to compare notes. I'm in the process of ordering the SPH bearing and possibly his PTP style chsssis.
Steve - E-mail: scoconis (at) gmail.com

RMcC
Hi Steve,
Yes, I have rebuilt several Lencos over the past 10 years using a CLD style plinth. There are very many variations on the CLD plinth of course. In my case I have pretty much stuck to the basic design that Jean Nantais published 20 years ago. I know, as I have just reviewed Jean's recent model, that the TJN Lencos have evolved quite a bit from his original CLD plinth. He is now using some special woods (he won't tell me what they are) and has modified the outside layers. I have never used the SPH bearing however I think that I may eventually buy one. I use the original Lenco bearing design in my Lenco rebuilds however I install new sleeves and a new ball, all available from your local bearing store.
I buy mine at General Bearing. I also replace the original Nylatron thrust pad, which was never designed to last 40 years, with a slightly thicker Acetron pad. It has less friction and is also very much harder to dimple that the Acetron pad. With respect to the PTP chassis, I have been contemplating contacting Peter Reinders for a review sample. That would mean building another turntable from scratch though!
If you want to "compare notes" that's fine. Keep in touch.
Roger McCuaig

Thanks for your Topping reviews!
Hi,
Thanks for reviewing the Topping PA3 and MX3, based on your informative and nicely written reviews, I decided to go with the PA3 as an amplifier for on my desk in my office. Will be using a pair of Dali Spektor 1 speakers.
Greetings from the Netherlands,
Martijn - E-mail: martijn.estor (at) gmail.com

LC
Dear Martijn
I'm glad you enjoyed my reviews, those amps are pure bargains, indeed. The PA3 will have no trouble at all driving your Dali Spektor 1 loudspeakers. Just keep us updated about your findings!
Happy listening!
Lucio Cadeddu

Audio Note Io1 review
Hi Graeme,
Nice review, sir. I have used one of these on numerous occasions and can 100% concur with you findings. Forgive me but can I assume the photos were taken before the cartridge was aligned? I ask as in the instructions for the arm/cartridge, the front of the head shell perfectly dissects the front head shell hole when correctly aligned and I tested this to be correct. I assume you'll be holding on to it too, if so, good choice. I can also inform that my Tom Evans Groove+SRX, MC only phonostage, set up for my Dynavector DRT-XV-1t has more than enough gain and ridiculous low noise floor to use this beauty. What ever you do don't audition the Gold!!!
Cheers,
Simon - E-mail: simonpcwalker (at) me.com

GB
Hi Simon,
Thanks for writing - glad you enjoyed the review. As for alignment according to my Polaris Plus protractor the alignment is correct in the photo! I checked again this evening and it's spot on on that position! May I ask which arm/TT combo you tried with the Io 1. I didn't get instructions so I relied on the protractor even though it looks a bit weird!
Thanks also for the phono stage info. Always good to know!
Kind regards,
Graeme Budd

Fidele Audio upgrades on NAD amp
Hi TNT, I've just finished reading your article on tnt-audio.com regarding the Fidele Audio upgrade to your NAD 3120 back in 2006. I bought a NAD 304 in 1995. This model is very similar to the 3020 in that the preamp and phono (MM only) stage are almost identical. The main difference being the power supply and power amp are a more modern design which includes some complex protection circuitry. A few months ago I decided to have the amp upgraded so I went online to find someone that could do this for me. That's when I came across Fidele Audio. I emailed Peter Hickman and he was happy to do the work. The upgrade was similar to your own which also included swapping out the caps for audio grade Nichicons and upgrading the resistors in the signal path to Vishay metal film type.
When the amp was returned to me I hooked it up to my NAD 514 CD player and NAD 804 speakers which was the system I'd been using since I bought the amp. I put a CD in the tray and hit the play button. To my dismay there wasn't a big improvement in sound quality overall. What there was however was a harshness to the high mids and treble frequencies that wasn't there prior to the upgrade. So much so that listening fatigue set in after a short period and I had to turn the amp off. The CD player and speakers were always a bit lively but no where near as harsh as this.
Did you notice an increase in this frequency range or something similar to my experience with your own upgrade?
Regards,
John - E-mail: jdowney9 (at) hotmail.com

LC
Dear John,
sad to hear about your disappointing NAD 304 upgrade! No, it is not normal at all, it should sound clearly better, not worse! The first thing to do would be to contact Fidele Audio and ask for some explaination. Secondly, I'd let the new components “break-in” for a while and see if something changes for the better. New, better components might add some extra liveliness to the mid/high range, but certainly not harshness! Consider that old passive components like caps and resistors tend to sound warmer, simply because they've lost the original electrical parameters and, hence, performance. This is way many audiophiles seem to prefer the odd warm and mellow sound of vintage components: simply, they do not sound like when they were new! The sound tends to slow down and becomes warmer.
Keep me updated, I'm curious!
Lucio Cadeddu

AudioEngine A1 speakers
David,
I've used the AE2 for several years now, connected to my iMac basically for background music. They are great speakers, even when you turn up the volume. I did try using my CD (Accuphase) and later incl my pre (Air Tight) and it makes a very impressive sound.
I think the changed from Class AB to D could be due to the heat as there is no external heat sink. My left speaker was affected my this. The mid/woofer cone deteriorated and crumbled! I have since replaced the mid/woofer cones with what I could get on the internet. Unfortunately they are not matched pairs (but they were cheap), so one much louder than the other. Sound better than my KEF Muo.
Just thought give some feedback as a user. Yes, I would still recommend them to anyone looking for a pair of small speaker.
Regards,
Teng - E-mail: ongtb6 (at) gmail.com

DH
Hello,
Thanks for the insights! I think both models are terrific values for the money, and I'm glad to hear someone out in the "real world" confirming my opinion that they are good performers, although I'm sorry to hear of your mishap with the one cone.
Happy listening to you!
David Hoehl

Bright Star Audio Isonode
Hi Mark,
I read your excellent review of Bright Star Audio's Isonode vibration absorbers and would like your opinion of which would be best for the following equipment?

  1. Yamaha 801 Integrated Amp - 26.2 lbs
  2. Cambridge Audio CXC - 10 lbs
  3. Ifi PowerStation 5 - 10 lbs
Kindly let me know?
Edward - E-mail: ejfroe (at) gmail.com

MW
Hi Edward
Thank you for your kind words about my articles. I am aware that they were written many years ago, but the findings still apply. I am guessing that you refer to the Bright Star Isonodes and that "Isonets" is the product of an enthusiastic spellchecker. Since then I have tried several similar alternatives from various sources and the Isonodes and the Bright Star Isonodes remain the best of the bunch and excellent value. They certainly win over fancy wire as a measurable and tangible and effective means of improving audio system performance.

As you have implied in your query, the weight of the component is the principle distinction between the choice of small or large Isonode. As you know, with hard feet I recommend three supports, but with soft feet any number is possible. I have found with Bright Star Isonodes (which I still use constantly) it is best first to establish three factors about each component:

  1. The mass of the component
  2. The centre of gravity of the component
  3. The parts of the component chassis most prone to vibration
  4. The ventilation holes

The small Isonodes can support up to 30 lbs max per set of four (I assume that you are writing from a non-metric location and Bright Star also live in the land of avoirdupois). Distribute these equally around the C of G at the most vibration prone areas. The large Isonodes can support up to 42lbs and I would choose these for your amplifier because it will enable you to place an inert mass (Victorian quarry tiles are effective and Barry Kohan can also sell you the Little Rock ballast) on top of four more small Isonodes on top of the amplifier for greater effect (the top plate is usually even more resonant than the chassis base).
I hope this is helpful.
Happy tweeking,
Mark, The Old Scribe

Trenner & Friedl SUN
Hi there,
I just read through the your review on Trenner & Friedl SUN speaker and really thanks for sharing your experience. Actually I could see for this speaker, the sensitivity is quite low. Thus how do you make sure it is driven properly? What amplifier did you use to drive it? I could see from somewhere that people drive Trenner & Friedl speakers with Jeff Rowland amp but I am not quite a fan of D-class amp. Want to know your opinion.
Thanks,
Eddie - E-mail: qijinpeng19 (at) gmail.com

LC
Dear Eddie,
yes, the sensitivity is very low, but this just implies you should use some extra watt to get your desired sound pressure level. There's no reason to use a particular technology (Class A/B/D/whatever) provided the amplifier can deliver good watts. And there's a limit to power handling, as well, do not forget the size of the drivers. As remarked in the review, you need good watts but you shouldn't exceed the natural limits of the drivers. How many watts? Well, that mainly depends on your listening habits and on the size of your listening room. As said, I believe that at least 30 good watts per channel are mandatory. Remember: quality is the keyword here, not power.
Happy listening!
Lucio Cadeddu

Aluminum cap for Denon DL-103
Hi Roger,
I've just read your 2018 review of the DL-103 with the aluminium cap.
It's been a while since I last used a stock 103, but I've used (and abused) at least 3 or 4 of them throughout the time. At some point, I removed the plastic body, which helped reduce some of the "plasticy" sound character, later I trued filing off a tiny bit of excess aluminium on the tip of the cantilever, which provided some needed treble and air.
I've also experimented quite a lot with decoupling the cart from the headshell, using different materials in order to reduce the amount of vibrations to move back up into the headshell and arm. All of these experiments provided audible improvements in my arm, which by that time was a primitive Fidelity Research FR-54.
Later, I've purchased a 103R, quite a lot better than the standard 103 if you ask me, and a better bargain too, even at the higher price. But with all my former experiments in mind. I used the decoupling and the filing the tip of the cantilever tweaks on this cart as well, and with splendid results. As I write this, the 103R is mounted in a mahogany body on an Audiomods Series VI arm. The plastic body of the cart has been removed entirely.
The decoupling was achieved by adding a VERY thin layer of bathroom silicone to the bottom of the mounting plate, and then screwing the mahogany body tightly to the mounting plate. The cart itself is glued inside the mahogany body, no screws here. I did have to operate on the mahogany body in order to use my available screws, but this won't be necessary for everyone; it simply depends on which screw lengths you have available.
The sound quality of this all put together is way beyond what I have ever dreamed of, and equally above any 103R I've ever heard before or since. The amazing silence of the extremely well damped arm sure plays a large part of the resulting sound quality, admitted, but having further reduced the vibrations of this rigid cart from wandering up the chain, certainly helped as well. I feel these tweaks should be tried out at TNT, either with a standard 103 or with a 103R, or both. It's worth it, I promise. But the 103 family seem to prefer extremely well damped arms in my opinion, so mounting it in a half decent SME arm won't cut it. Metal tubes is not the favorite arms for a 103 IMO.
In case you'd like to copy this to your website in order to share it with your readers, you are most welcome, and if you have questions about anything, I will do my best to provide any and all details about these tweak procedures.
Sincerely,
Keld - E-mail: saintkelo (at) gmail.com

[Audiomods Denon DL103]

RMcC
Hi Keld,
Thank you for your interesting email!
Enjoy your music,
Roger McCuaig

Linn Index mk1 loudspeakers
Hi, I recently purchased a pair of Linn Index mk1 speakers. Initially I drove them with AIWA 8100 amp: very boxy, thin sound. I had just purchased a mint 8100A AUDIOLAB AMP. I wired the Audiolab to the Index...what a beautifully balanced top end and to me a nice moderate bass. I think these are the true LINN SOUND as they were the first Linn produced. To me 100 eur very well spent!
Regards my friend, let me know if you do a piece on this.
Tony - E-mail: tonymcdonagh635 (at) gmail.com

LC
Dear Tony,
I reviewed the second version of these babies, the Index Plus, no plans to review a first series model, which is also extremely hard to find, especially if you don't live in the UK. As far as I know, the Plus's were definitely better sounding, but it seems even the first series can be extremely satisfying. Place them very close to the rear wall if you need more bass output, as they were designed to be placed this way. Your 100€ have been well spent, that's for sure!
And, please, do not use Aiwa amplifiers anymore! :-)
Happy listening!
Lucio Cadeddu

Sure TA2024
Dear TNT,
I am writing for an advice on the small Sure 2024 amp. I have a pair of Acuhorn 125's, used with various (even expensive) class D amps, all inflating the mid-bass. I jokingly tried a TPA3116 which wasn't too bad considering the cost. Reading various things I read that the 2024 was more refined in the upper midrange, or simply with less bass it brings out the top end better...
Well it was true, I stuck this little amp in my full range amps and it seemed to work very well (at least in my room). My question is: Does it make sense to use it as a power amp since it has volume?
Maybe I should get a Trends Audio TA-10.2P?
Best Regards,
Riccardo - E-mail: baruzziriccardo (at) gmail.com

LC
Dear Riccardo,
of course you can use the Sure TA2024 with its volume set at its max. On the other hand, using two potentiometers isn't a good idea, even if it works. I'd prefer to use a TA2024 without volume control. Either you remove it from your Sure TA2024 or you purchase a (better sounding) Trends TA10.2 P.
Happy listening!
Lucio Cadeddu

Caveat Emptor article
Dear Roger,
in response to your last article on the caveat emptor mantra, I'd like suggest a different perspective.
First, you should have considered the main factor in commercial experience like yours: geolocation.
I can only speak for my little provincial, empire's borders experience, here in Naples, Italy.
I'm old enough to have passed through the roaring eighties (here, they were particularly “roaring...”), the shimmering nineties, and so on... I missed the seventies, but I suspect that, while a wonderful period of blooming companies, product, ideas, and so on, it is also a period tendentially over-praised by the people that “were there and made it through”.
Well, I still remember a shop in the city's most elegant shopping district, that sold furniture at street level, but in its windows showed off all high-end (they were not bearing such a label, then...) audio goodies, that were sold in the huge basement level. I still remember hangin' out there after school on the way back home, or in some homework-free afternoon, listening to wonderful gear; the systems often playing for “real”, paying customers (there has been a time when there were some of those, rest assured :-)), but also sometimes switched on just for “us kids” (contrary to the common sense, in places like that one, nerds are never alone...).
I NEVER was one of their customers, and they knew it well, since they “weighted” me and my “economical force” as soon as I walked in. But I was polite, always clearly “exploring” and never asking attention for myself; so, they didn't bother having me there, actually even inviting me to audition something new or an unusual setup. I'm sure that in their commercial dealings they sought - and got - a robust profit, but I can't recall a hearsay of bad reputation: they asked steep prices, but that was according to the gear they were selling (and the customers they dealt with), and they gave an after-purchase service, albeit minimal (setting up the system in the buyer's home, coming to that places in case of faults, even just for taking the faulty component and send it to the - very few - repair services, and so on...).
This all could be possible in such a small environment, like the one where we all lived, buyers and sellers. That kind of “commerce” couldn't be thought of without the personal contact between the parts, and the immediate - “social”, we'd say now - resonance that a bad move from either part would have had. That's quite different, I think, from US o Canadian experience, where the retailer's clients come from everywhere, from many miles away, eventually seeing each other just a couple of times in their lifetime. It seems only a one-to-one affair...
Second, you are suggesting that the retailer is there mainly to see you as a spring of (part of the) money flow he needs to get along with the business. He is NOT there to be you FRIEND. Well, that's another point that I think is strictly connected with the “geolocation” I was talking before.
Since high school, I ended up visiting mainly another store (the previous one suffered a forced change in location and the market was getting more into the snobbish high-end area; both things sent me away from them). This second store was managed by a well known high-end artisanal producer and, mainly, by its son, who is slightly older than me. I' not meaning we've become FRIENDS, but I can assure you that he had and still has an attitude towards all his “clients” more like a bartender than a retailer. He not always “tolerates” us hangin' out there, but often urged us to do so. We “used” its place also as a “hub” for the “audiophile community”, passing by also (mostly) when we didn't need to buy anything, just to “listen to what's new”; and now it is one of the few places where important brands show off (until it was permitted...) their news.
Sure, in his business operation he seeks his profit, but I still don't recall any hearsay about mistreated customers. Unfortunately, our market shrank, because so many of us lost almost all their buying potential, eroded by the shortage in work and payments and the rise of life's costs. So, there's a big resurgence of the second-hand market, and this tends to be - I guess - his main “cashflow” source. In selling used gear, he, as a salesman, surely is charging more that the buyer could spend buying directly from the former owner, and surely part of its “selling weapons” is the audiophile reputation of the used gear he is selling, thus unavoidably depending on (and endorsing) the snake oil that things come with; but he is anyway still letting used gear move, since he provides that sort of aftermarket light assistance I described before (even home auditions...), plus he still tends to be the “center” of our little audio circle. It is always not only a commercial experience, not only a buy/sell meeting of wills. I think his attitude couldn't have followed this path, were we placed in an area where clients are spread over long distances, just like seems to be there, “over the pond”.
Here's a recent article on the Sound and Vision Website. There, I seem to read a similar view, especially in the comment section: clients accustomed to travel a long way to interface with the retailer only, well, for the sale.
In conclusion, I'm just suggesting that the picture you are describing isn't always so dark. And that in many places - especially where people are used NOT to have much money in their pockets - the “caveat emptor” function is always on (hence, our now radical mistrust of EVERY politician and our pathological difficulty to undergo the exercise of public powers; but that's another story...).
I think that, more than that sane distrust (a pretty good rendering from the Latin origin of this word), maybe the real safety belt for the purchaser can be a community; acting as a soloist is usually never as good as playing in a group :-)
Then, if you want to sink in the swamps of the fictious pseudoscience that the marketing guys place their products in, you are free to do it, provided you're with someone who can help you in the decision. And if four eyes see the same things that two do, so be it, enjoy what you got and start listen to some music :-)
Thank you for having followed my ramblings until their ends.
Regards,
Carlo - E-mail: md1809 (at) mclink.it

RMcC
Hi Carlo,
Thanks very much for sending us your different perspective on this subject. Always good to read about other peoples experiences.
Enjoy the music,
Roger McCuaig

Yamaha A320 review
Good evening Lucio,
I've read your nice review regarding the A320. Have you already recapped it? Do you have a schematic or service manual? I'd like to tweak my 320 and more insights about this amp are welcome.
Thanks in advance,
Kind regards,
Bram - E-mail: rheingold (at) ziggo.nl

[Yamaha A320 - vintage audiophile amplifier]

LC
Dear Bram,
glad to know you enjoyed reading my review of the A320. It's a little gem, indeed, and mostly unknown. And no, I haven't recapped it yet, it sounds very good even “as is”. In any case, it has found its place on my vintage collection shelves, I'll leave it there and use it for some comparison from time to time. I don't have a schematic or a service manual, unfortunately, but it is a very simple amplifier, anyone can look at it and understand its secrets. Moreover, you don't need a schematic or a service manual to recap it, just remove the old caps and solder the new ones. You can replace other passive components here and there, just to be sure. Just keep me updated on your project...
Happy tweaking and listening!
Lucio Cadeddu

Loudspeaker damping
Hi Mark,
after reading your 3 part series on TNT-Audio.com regarding loudspeaker damping, I was hoping I could get your help. I'm building my first DIY speaker. I attached the design notes and cabinet plans. These come with pre-built cabinets just like the plans, no internal bracing. They only come with acousta-stuff for loose fill and this simple foam to line the walls: www.madisoundspeakerstore.com/acoustic-damping/dampers-foam-sheet-27-x-42-x-5/8/

How would you recommend to dampen these? For example, I can add dowels to cross brace. I'm also intrigued by this product. I want to retain the liveliness through the midrange. I don't mind a bit of bass warmth from the MDF's natural 250Hz and 500Hz resonance frequencies if it keeps the midrange pure and lively.
Another option is to substitute this for the foam for the interior walls: www.madisoundspeakerstore.com/acoustic-damping/wool-felt-1/4-thick-x-36-wide-by-running-yard/.
Greg - E-mail: johnson.greg924 (at) gmail.com

MW
Hi Greg,
Thanks for giving damping material such consideration and for considering my article an authority on the subject.

I'm guessing that the 3/4 inch mdf cabinet come ready routed for the drivers. Therefore there is little mdf supporting that woofer rim, especially close to the tweeter recess. Any cabinet front (known as the baffle) movement (vibration) at this point, caused as a reaction to the bass cone mass movement, Will have a disproportionate effect on the tiny treble signal from the tweeter. This causes intermodulation distortion, a non-linear distortion which is one of the most unpleasant artefacts in audio.

Hence, task Number 1 is to stiffen that baffle with braces at that point. As you have used imperial measurements I will stick with those. Any offcut of dense hardwood (balsa is a hardwood and far from dense, so that was no tautology) like oak, beech or one of the denser maples will suffice. 1/2" X 1/2" square section is enough in this location from the cabinet top down to the top of the bass=mid unit and from just above the slot vent diagonally in toward the bass-mid aperture.

As you suggest, hardwood dowels across the cabinet void will also help and will provide support to the stuffing. Sound absorbing layers on the walls help reduce reflections back at the bass-mid driver (paper coned in this instance) up to the frequency 1/4 wavelength equivalent to the thickness of the absorbing material. The Madisound foam sheet you link is 5/8" which in SI is 0.016m from 5kHz upwards which is therefore not useful on the cabinet sides.

Acry-Tech Acoust-X Paintable Damping Material is a different proposition. It's surface texture will scatter reflections and its composition will convert some energy into heat and its mass will lower the Q and the frequency of cabinet wall vibration. I suggest a both-and approach.

Centrally supported sound absorbing material (Acoustistuff, long-fibre wool, acoustic foam) best absorbs standing waves in the cabinet. A roll of the Madisound foam sheet will also achieve this, thus avoiding acoustistuff sag. Hence a front-back dowel close to that critical baffles weakness around the tweeter and bass unit apertures is a good idea piercing a roll of the Madisound foam.. Two dowels between the sides will help equally with strong 2 pack adhesive in every case (Aerolite 606 or similar measures better than pva in this context). The roll can be between the top side-to-side dowel and the front baffle and between the bottom side-to-side dowel and the rear. A further layer of foam on the bottom face of the loudspeaker exactly below the driver will reduce an early reflection there, especially if sculpted away from the driver. Having said that, do not overdo the damping or the port alignment will change and be ineffective. I note that Seas suggest playing with damping in the port according to loudspeaker location. The true function of a loudspeaker port is not some kind of magic to conjure bass where there was none before (ye canna change the laws of physics captain) but to control the bass driver/cabinet air volume resonant peak (hence the classic reflex double impedance peak) so damp the cabinet not the port air flow.

Seas make some excellent drivers, many of which I've used over the years. The kit you have chosen is based on an OEM complete loudspeaker system that they made that was badged Dynaco A25. It dates back to the audo heyday of the Summer of Love in 1969. They shifted over a million pairs so listeners must have loved them. Fabric dome tweeters tend to sound less like a series of resonances than plastic domes to the Old Scribe ears. Paper cones tend to sound faster and livelier than the heavy bextrene cones of the classic British sound of the same period, at the expense of a little midrange colouration.

On the other hand, mdf is the most life sapping loudspeaker cabinet material ever devised by humankind. Resonances subtract (known appropriately as destructive resonances) as well as add. Bracing is therefore strongly recommended. Even better is adding a layer of 1/4" hardwood sheet instead of veneer to the outside of the sides, top, bottom and back of the cabinet instead of veneer. You could do this later so that you can hear the difference, or do it now and get it over with! As long as you round the corners of the 1/4" hardwood sheet there will be no effect on the baffle step frequency. The most available and cost-effective material I have found for this is sold as kits to rejuvenate wood flooring.

Another future-proofing idea is to connect the drive units to two sets of terminals on the rear of the cabinet. Mount the crossover on the outside so that it is not affected by the hostile vibrations in the cabinet. Later you might choose to experiment with a higher spec tweeter capacitor or even with active drive and this makes that easy.

I would anticipate that these loudspeakers will give you hours of fun making them and even more hours enjoying them. You also get the delight of saying "I made them!"

Do please keep me updated with your project progress.

Happy building and listening,
Mark Wheeler

Lenco 75 platter ringing
Howdie
I just read an article on TNT and not sure what exactly was done to the platter. The picture is too small...I applied same stuff as you underneath - around inner thin (deep) rim but after placing it back on a spindle platter doesnt move :)
Where is the catch?
Thank you
Arunas - E-mail: uksminas (at) gmail.com

RMcC
Howdie to you too,
the most probable cause for your problem would be that the platter is rubbing on the platter brake. This is more likely to happen with an L78 due to the design of the brake however it could still happen on an L75. Especially if the material that you applied is thicker than about 2.5 mm. On an L78 the rubber brake pad can be filed or sanded down a bit to accomodate the added insulation. On an L75 it is a bit more difficult. You can try bending the brake lever which is made of a springy metal or cutting off the end to shorten it by 1 or 2 mm.
If you are having trouble viewing the photos on the web page correctly I suggest that you try changing web browser. Sometimes that has worked for me.
Enjoy your music,
Roger McCuaig

Love your site
Greetings from Jasper,
I just purchased some vintage audio kit. I am a MacHead and a collector of vintage devices. I am always enriched by the discovery of the knowledge base provided by a site such as yours. I am curious to know if there is a monthly newsletter I might subscribe to?
I have book marked your page and will be a regular visitor.
Thanks again!
Dave - E-mail: betabake (at) gmail.com

LC
Dear Dave,
we don't publish a monthly newsletter, as we update our website every weekend, with new reviews and articles! You can bookmark the What's New page and visit it regularly on weekends. You can even stay in touch with our updates via our official Facebok Page.
Glad to hear you love vintage gear! We do love good vintage components as well. Unfortunately, nowadays, everything from the Seventies and the Eighties is now considered vintage, even if it was bad sounding back in its days! From time to time we publish reviews of vintage components we love and, moreover, we have an entire section of the website, titled “On an Overgrown Pathé”, devoted to REALLY old components of the pre-LP era.
Hope this helps,
Lucio Cadeddu

Decca tonearm
Hello sirs,
searching informations on a vintage Decca original tonearm, I saw you review dating from 2008....and I thought you could maybe help me: having bought few months ago a wonderful Decca MKII stereo cartridge, I purchased just after an original Decca Tonearm.
But I don't have the "plan" to install it properly on the turnable ( a Garrard 401 )...! (it was not included with the arm). Would you know where to find the right one, very precise?
Just in case.....thanks in advance,
All the best,
J-M - E-mail: jmharari (at) gmail.com

LC
Dear J-M,
the instruction for proper tonearm installation heavily depend on the turntable where you will install it! In any case, assuming you have purchased the same tonearm I have (New in Box! A London International) these are the two pages of installation from the original manual...

[Decca tonearm installation instructions]
[Decca tonearm installation instructions]
Hope this helps,
Lucio Cadeddu

Headphones choice
Dear Arvind,
I'm Pierluigi and I've been a TNT-Audio reader for many many years. I've recently enjoyed your article about the AK OB1 DIY loudspeaker project. I found very very interesting technical aspects in it especially the open baffle design (and the fact that is diy). Great project but my question is not about the AK OB1, or maybe a quest that can be related: the AKG K 701 in your referenge gear: I was watching that headphones for some time now and I'm curious to ask an opinion to someone that have listen to them for some time, what are the strengths and the weaknesses or why that headphones are appealing to you? One of my thoughts is that being open back maybe the sound character is comparable to the naturalness of the open baffle speakers? Speaking of headphones actually my gear is: Sennheiser HD 600 for open back (21 years old now), ESS 422H for closed back, Fiio X5 gen. 3 as source (and dac) and a Fiio A5 as amplifier, I think that the HD 600 is a bit old because it starts to lack something, I remember another sound from it (or maybe I'm wrong) and I'm searching for a substitute. TNT-Audio to me is the most reliable source of information because it's not affiliated to any brand, the opinions are genuine and the authors are passionate people about hi-fi, so here I am. Please give your honest opinion about the K701, I will consider it as pure gold because for now I got only biased reviews but not a truly honest one. If it doesn't disturb you I would like to thank you for your precious time even if only for reading my words and I hope to have an answer.
Thank you very much and greetings from Italy.
Pierluigi - E-mail: wigi__ (at) alice.it

AK
Hi, Pierluigi,
Thanks for your kind words, and glad you enjoyed the articles. See these comparison I had done a while back; see here. Subsequently, I picked up a pair of the 701s and directly compared to the Sennheiser HD650, and much preferred the AKG. Additionally, I have since acquired a pair of the Stax SR-44, and prefer the AKG's again. For as good as the AKG's are and as little as I use headphones, I have not had any more curiosity since I picked up the 701's. If I had, I'd also check out many of the newer electrostatic models.
I hope this helps.
Arvind Kohli

Digital Audio
Roger,
I read the review of the DAC and I feel a headache coming on...why? The hum problem. Like you...I abandoned digital in 2007 to concentrate on Analog. Fast forward to 2021, I love analog and own the following:

Currently using a passive preamp which works really well just curious about trying the Doge 8. I will eventually get the Doge 7 D/A. I am thinking of getting back to digital. The reason why I got out of digital, I cannot get into the music with digital. I play digital for awhile but then switch back to analog and relax. I hope after a hiatus of more than 10+ years out of the digital game...it has improved. I assume there is no way digital can sound as good as analog even in the higher sampling rates...am I wrong?
Ren - E-mail: renantebarroga (at) gmail.com

RMcC
Ren,
Well I see that you have lots of toys to play with!
You are asking yourself THE question; can digital sound as good as analog? Today, you have put the question to me,I feel the weight of the world on my shoulders .....As is the case with many of us, I have been asking myself that question too.
I believe that digital music does not sound the same as analog, and probably never will. That doesn't necessarily make one of the other better, it just makes them different. I personally prefer analog for several reasons; it is what I grew up with, I love the look and feel of the record and to experience the artwork, and of course the special listening experience of vinyl playback.
My experience, as well as some of my audiophile friends, has been that over the past few years digital playback quality has improved immensely. I believe that it is for the most part due to improvements in DAC chips. I recently had the opportunity to review a new unit that has two of the latest ESS DAC chips in it and I found it very impressive. (review to be published soon) But a good DAC chip is just the start, a digital playback device has to be designed with the same attention to detail and component quality as is given to high-end analog equipment and that means not just the DAC chip but also the analog section, the power supply, everything.
In conclusion, I would say that there are digital music components available today that can deliver anything and everything that a top quality vinyl playback system can deliver with not a trace of "digital fatigue". Some days I listen to digital music all day long played from my music server PC running JPLAY FEMTO into my Doge 7 tube DAC, but it doesn't sound the same. Nothing sounds the same as vinyl.
One cannot speak on this subject without mentionning the significant problem of digital music compression, AKA The Loudness War! Great playback equipment can't correct some of the terrible things being done in the recording studios.
So, there you have my take on the subject. Hope you get something of use out of it!
Enjoy the music,
Roger McCuaig

Dodge 8 preamp review
Hi,
I liked the review of the preamp...any chance you will cover the dac? I live in Montreal and I am assuming you like in Ontario, I was wondering how your experience with ordering the Dodge 8 preamp directly from Doge. Aamy problems or concerns?
Thanks
Ren - E-mail: renantebarroga (at) gmail.com

[Doge 7 front view]

RMcC
Hi Ren,
Nice to hear from you. I did write a review of the Doge 7 Tube DAC back in 2018. With respect to ordering from Doge, everything went smoothly for me and I had no complaints. (yes, I live in the Ottawa area) Now it is possible that the Covid situation has had some impact of their operations so I would suggest that you ask them directly what the situation is before placing an order.
Enjoy your music,
Roger McCuaig

Caps data
Dear TNT,
how does one calculate the speed V/uS for capacitors? I noticed this in this TNT-Audio article and I am interested in comparing and the equation would be appreciated. For bass applications, would it matter for the slew rate to get higher than 50V/uS?
Thanks,
Trevor - E-mail: tvormittiag (at) cogeco.ca

GP
I cannot find any data or info about capacitor speed in terms of V/us values. The values you find on high quality caps data sheets (for example https://www.elna.co.jp/en/capacitor/alumi/catalog/pdf/rkc_e_p140-141.pdf) are ESR equivalent series resistance Rated ripple current. ESR is easy to understand: in capacitor models there always is some resistance due to leads, electrodes and other inner components impedence: this is what is limiting the current in a capacitor (at least at audio frequencies), and is therefore directly correlated to speed.
However, a capacitor subject to a high current flow heats up, so you must limit the current if you want to assure a reasonable life time to a cap (http://www.rubycon.co.jp/en/products/alumi/pdf/ChargeDischarge.pdf).
Calculations of speed and current in a given configuration, however, are not so simple, the only solution is simulation of the circuit (https://forum.allaboutcircuits.com/threads/calculating-ripple-current-in-a-capacitor.154511/).
This requires an appropriate simulation model (http://www.iequalscdvdt.com/cap_model.html for a discussion of a proper model) and a simulation environment (LTSpice or similar).
Hope this helps,
Giorgio Pozzoli

Clarifications about TNT AIRCOIL
Hello Roger,
First of all, thank you for the information, tips and articles that you wrote on TNTaudio, they are always interesting and useful!
I am writing to you to have some clarification about the cable in question, the TNT AIRCOIL, actually I followed the project that you described, in order to create an RCA - JACK3.5 cable to be able to connect a DAP to the integrated amplifier (an excellent example of NAD3020i whose tone I love), in my opinion, and without still making resistance and capacitance measurements, this cable sounds good, is neutral and transparent and has a lot of dynamics.
The comparison, by ear, is with the homemade TNT SHIELD cable. As conductors I used an AWG23 of a CAT6, but I did not find information on either the quality of the copper or the type of insulation. The cable is made up of two conductors for each channel (one for heat and one for cold) which are intertwined alternately in a single Teflon tube. On the RCA side, on the other hand, I adopted two pieces of Teflon for each channel and twisted to 2.
My explanations:

I apologize for the inconvenience caused, and for my poor school English (thank goodness that google translate exists ... hehehe) and above all for any wrong written information, I am a novice of audiophile environment, but I am trying to document and learn.
Thank you in advance, let me know if something is not really clear.
Best regards,
Dimitri - E-mail: skadym (at) gmail.com

RMcC
Hi Dimitri,
Thanks for your email. I have used both CAT5E and CAT6 cables as sources for the conductors used to build my Aircoil projects. I always try to find "Plenum Rated" cable as this means that the conductor insulation will be Teflon and not HDPE.(high density polyethylene) Teflon has a better dielectric constant. (less electric charge is stored in the insulation) Now there are certainly some people who would argue that, in this application, the difference is so tiny that it is of no consequence, and they may be right. My reasoning is simply that the cost difference is very small (in some cases I got the cable for free!) so why not use the Teflon insulated conductors. I did read someplace that CAT5E and CAT6 cable are made with 99% pure copper, however, I certainly wouldn't claim that to be an absolute truth. One thing is known, CAT6 UTP (Unshielded Twisted Pair) is capable of transmitting data at 250 MHz so our 20 KHz audio signal is not a challenge.
With respect to your cable design I'm sorry to say that I have not been able to fully understand your description so I will have to abstain from any comment on that. Maybe you could send me a sketch of photos?
Now for the noise problem associated with unplugging the cable from the DAP, well, this is quite common and the best advice that I can give you is never leave a cable connected to an amplifier or preamp input with nothing connected to the source end. It's not a good practice.
Enjoy your music,
Roger McCuaig

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